Sensitivity-selectivity balance in mass sensors: the case of metalloporphyrins

The influence of peripheral alkyl substituents on the sensing behaviour of metalloporphyrin-based Thickness Shear Mode Resonating sensors (TSMRs) has been investigated. The presence of the alkyl chains improves the metalloporphyrin thin film permeability but at the same time increases the magnitude of non-specific interactions, reducing the influence of the intrinsic metalloporphyrin selectivity. The butyloxy derivative 2 represents a good example of a compromise between these opposite effects, where the short alkyl chain is able to increase the sensitivity and response time behaviour of the TSMR sensor, without significant loss of the selectivity properties.